Self-lubricating bearing



Jan 16 1940. E. B. MERRIMAN 2 187 626 SELF-LUBRICATING BEARING Filed July 2, 1938 Invewlbr mama J. 1c, 1040.

UNITED STATES PATENT OFFICE Application July 2, 1938, Scrlal No. 217,239

ZCIalms.

My invention relates to metal bearings which are self-lubricated by means of a solid lubricant contained in spaced pockets formed in the surface of the bearing, and is particularly applicable to expansion plates such as are used to carry the ends of bridge spans and provide for their expansion and contraction resulting from the changes in temperature to which they are subjected.

The lubrication of a bearing of the type above referred to depends upon the spreading of a thin coating of the lubricant over the metal surface between the pockets, which overlap laterally and preferably occupy, collectively, from ten to thirty per cent of the total surface area of the bearing,

and in these bearings as usually constructed heretofore the pockets are of a compact circular shape and the distance between consecutive pockets is much greater than their diameter. Such pockets, however, are unsuitable for use in 0 an expansion plate, for the reason that the range of the reciprocating movement of the span carried by the plate is so slight that the lubrication will be incomplete, and correspondingly ineflicient, unless the consecutive pockets are so close 35 together that their aggregate area is excessive.

My invention overcomes this difliculty by the provision of a bearing in which the pockets of lubricant are given a novel configuration that enables them to be located as close to one another as the 30 conditions to be met may require, while still keeping their aggregate area within permissible limits.

In the accompanying drawing,

Figure 1 is a plan view of a portion of a bearing embodying my invention in its preferred form, as

a designed for use as an expansion plate for bridge spans;

Figure 2 is a section on the line 2-2 in Figure Figure 3 is a plan view similar to Figure 1 but 0 illustrating a modification;

Figure 4 is a side elevation of a tool for use in the manufacture of the bearing shown in Figures 1 and 2; and

Figure 5 is a face view of the cutting end of the 5 tool shown in Figure 4.

The bearing illustrated in the drawing comprises a metal plate Ill, preferably made of bronze, which is adapted to rest and be held in fixed position on a bridge pier or other supporting struco ture and has a flat top surface on which the complementary member of the bearing moves back and forth. In the case of a bridge span, this complementary member will ordinarily consist of a steel shoe secured to one end of the span and having a flat under u ace or ab ut the s me area as the top surface of the plate It, such shoes being well known and constituting no part of my invention.

The plate It may have any desired dimensions, according to the weight of its intended load, and its top surface is provided with pockets l I hereinafter described in detail. These pockets are filled with a lubricating material l2 in solid form, which may be any of the lubricants already in common use in self-lubricating bushings.

The pockets l l differ from the compact circular pockets heretofore employed, in that they have an annular contour which gives the lubricant the form of bands having a substantial linear dimension but relatively narrow, thereby making it possible to locate adjacent pockets in overlapping relation both in the direction in which movement on the bearing takes place and transversely to that direction, as shown, and in such proximity to one another that the range of the movement is sufficient to cover the intervening metal areas without requiring the area of the collective pockets to be increased beyond what is customary. In other words, the result is equivalent to expanding the effective area of the lubricant, without increasing its actual area, to such an extent that the spreading movement suflices to distribute the lubricant over the entire metal surface of the bearing and thereby secure maximum efliciency.

The annular pockets shown in Figures 1 and 3 may be readily formed by a boring operation using a cylindrical tool with a ring of cutting teeth on one end, like a trepan, such a tool being illustrated in Figures 4 and 5, in which it indicates the body of the tool and I4 indicates its cutting teeth. In order to locate the tool accurately and steady it during the boring operation, I prefer to provide it with a central pin l5 extending a short distance beyond the teeth 14 and adapted to enter and be guided by a hole is drilled in the plate i0, Figures 1 and 2, at the center of each pocket ll,

these holes being drilled as a first step in the formation of the pockets. Their depth is sufficient to permit the pockets II to be given the desired depth, and eventually they are filled with the lubricant, which contributes to the coating of the metal surface within the pockets Ii and is taken into account in determining the total surface area of lubricant to be employed.

Bridge plates are best made of rolled bronze or bronze alloy, in which the lubricant pockets have to be formed by boring operations, and since the machining of this material is expensive on account of its density and toughness, one of the advantages resulting from my invention is that the employment of annular pockets enables such plates to be constructed with a minimum number of pockets, as compared with any other arrangement of bored pockets which will give complete lubrication without unduly increasing the surface area oi the lubricant in relation to the area. of the exposed metal surface.

The annular pockets, however, may obviously be employed in bearings made in various ways or used for various purposes, orhaving other than flat surfaces, and if they are formed in curved surfaces the use of a steadying pin on the boring tool, as described above, is particularly advantageous in preventing side play of the tool. It will also be evident that the width as well as the diam,- eter of the pockets may be varied and proportioned to produce any desired ratio between the area occupied by the collective pockets and the total area of the surface in which they are formed, without losing the benefit 01 the wide distribution or the lubricant which is made possible by giving it the form of relatively long and narrow bands.

I claim:

1. A self-lubricating bearing comprising a body portion provided with annular pockets which are filled with a solid lubricant and are spaced to overlap in the direction of movement on the bearing.

2. A self-lubricating bearing comprising a body portion provided with spaced pockets of annular shape and with a hole located at the center of each pocket and having a somewhat greater depth, said pockets and holes being filled with a solid lubricant.

EDWARD B. MERRIMAN. 

